SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'aa50fb498519bfd8b0da55485ef81c8428e2d64c0ad8db21a2b0476f0b7662ab' 
  AND token = 'SA5nD7qxRhtwBhIO0FYZDx6JrszOL7wiHgP13O2AUdc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}